ML032880409

Special Report 3-SR-2003-04 Regarding Boron Deposit at Control Element Drive Mechanism Vents

ML032880409
Person / Time
Site:	Palo Verde
Issue date:	10/01/2003
From:	Mauldin D Arizona Public Service Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
192-01127-CDM/RAS, EA-03-009 3-SR-2003-004
Download: ML032880409 (5)

Text

4C EA-03-009 David Mauldin Mce President Mail Station 7605 Palo Verde Nuclear Nuclear Engineering TEL (623) 393-5553 P.O. Box 52034 Generating Station and Support FAX (623) 393-6077 Phoenix, AZ 85072-2034 192-01127-CDMWRAS October 1, 2003 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station P1-37 Washington, DC 20555-0001

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 3 Docket No. STN 50-530 Special Report 3-SR-2003-004 Report of Boron Deposit at Control Element Drive Mechanism Vents

Dear Sirs:

Attached please find Special Report 3-SR-2003-004 prepared and submitted by Arizona Public Service (APS) pursuant to NRC Order EA-03-009 (Order), dated February 11, 2003.Section IV.D of the Order requires licensees to perform certain visual inspections to identify potential boric acid leaks from pressure-retaining components above the Reactor Pressure Vessel (RPV) head.Section IV.E of the Order requires licensees to submit reports detailing the inspection results within sixty (60) days after returning plants to operation.

This special report details the results of visual inspections performed at PVNGS Unit 3 subsequent to an unplanned reactor trip on July 28, 2003. The visual inspections were performed in accordance with the Boric Acid Corrosion Prevention Program which APS implements to identify and prevent boric acid corrosion of reactor pressure boundary components.

In accordance with 10 CFR 50.4(b)(1), copies of this report are being provided to the Region IV Administrator and the Palo Verde NRC Senior Resident Inspector.

A member of the STARS (Strategic Teaming and Resource Sharing) Alliance Callaway

• Comanche Peak

• Diablo Canyon

• Palo Verde

• South Texas Project

• Wolf Creek

Special Report 3-SR-2003-004 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Page 2 No commitments are being made to the NRC by this letter. If you have questions regarding this submittal, please contact Dan Marks, Section Leader, Compliance, at (623) 393-6492.

SincereY CDM/RAS/ras Attachment cc: B. S. Mallett, Region IV Administrator M. B. Fields, PVNGS Project Manager N. L. Salgado, Sr. Resident Inspector Assistant General Counsel for Materials Litigation and Enforcement Rulemaking and Adjudication Staff

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Attachment Palo Verde Nuclear Generating Station Unit 3 Special Report No. 3-SR-2003-004 Boron Deposit Found at Control Element Drive Mechanism Vent Docket No. STN 50-530 Reporting Requirement:

The NRC Order EA-03-009, "Interim Inspection Requirements for Reactor Pressure Vessel Heads at Pressurized Water Reactors," (accession number ML0303804700),

dated February 11, 2003,Section IV.D requires that certain visual inspections be performed to identify potential boric acid leaks from pressure-retaining components above the reactor pressure vessel (RPV) head.

Additionally,Section IV.E of the NRC Order requires that licensees submit reports detailing the inspection results performed per section IV.D within sixty (60) days after returning the plant to operation if a leak or boron deposit was found during the inspection.

Background:

On July 28, 2003, Palo Verde Unit 3 experienced an automatic reactor trip from approximately 98% rated thermal power due to reduced reactor coolant system flow when the main turbine tripped during a grid perturbation (reference Event Notification #40029). Subsequent to the reactor trip, routine visual inspections were performed in accordance with the Boric Acid Corrosion Prevention Program (APS procedure 70TI-9ZC01). APS implemented the Boric Acid Corrosion Prevention Program to prevent boric acid corrosion of reactor pressure boundary components and to ensure the requirements contained in USNRC Generic Letter No. 88-05, "Boric Acid Corrosion of Carbon Steel Reactor Pressure Boundary Components in PWR Plants" are met.

Report Detailing Inspection Results:

During boric acid walk-downs on July 29, 2003, two Unit 3 boric acid residue sites were identified above the RPV head. The sites were located on the Versa-Vents for control element drive mechanisms (CEDM) nos. 51 and 73. These sites exhibited no evidence of being active leaks and the boric acid residue did not contact the RPV head or related insulation. The source of the boric acid residue was most likely the vent ball / seating surface interface of the Versa-Vents.

Versa-Vents for CEDMs 51 and 73 were cleaned and reworked during the outage following the Unit 3 trip.

Unit 3 was returned to operation (Mode 1) on August 4, 2003.

Palo Verde Nuclear Generating Station Unit 3 Special Report No. 3-SR-2003-001 Boron Deposit Found at Control Element Drive Mechanism Vents 73 Docket No. STN 50-530 (CEDM Vent 73 As-Found Condition)

(CEDM Vent 73 As-Left Condition)

Palo Verde Nuclear Generating Station Unit 3 Special Report No. 3-SR-2003-004 Boron Deposit Found at Control Element Drive Mechanism Vents 51 and 73 Docket No. STN 50-530 (CEDM Vent 51 As-Found Condition)

(CEDM Vent 51 As-Left Condition)